Ectopic EWS/FLI expression is tolerated in both human and mouse-derive mesenchymal stem cells (Riggi et al., 2005, 2008; Miyagawa et al., 2008) and the subsequent EWS/FLI-mediated gene signature closely parallels that observed in patient-derived cell lines and primary tumor samples (Miyagawa et al., 2008; Riggi et al., 2008). This evidence concerns the gene EWSR1 and neoplasm.